Comparative Structure-Property Characterization of Poly(3-Hydroxybutyrate-Co-3-Hydroxyvalerate)s Films under Hydrolytic and Enzymatic Degradation: Finding a Transition Point in 3-Hydroxyvalerate Content

Abstract

The hydrolytic and enzymatic degradation of polymer films of poly(3-hydroxybutyrate) (PHB) of different molecular mass and its copolymers with 3-hydroxyvalerate (PHBV) of different 3-hydroxyvalerate (3-HV) content and molecular mass, 3-hydroxy-4-methylvalerate (PHB4MV), and polyethylene glycol (PHBV-PEG) produced by the Azotobacter chroococcum 7B by controlled biosynthesis technique were studied under in vitro model conditions. The changes in the physicochemical properties of the polymers during their in vitro degradation in the pancreatic lipase solution and in phosphate-buffered saline for a long time (183 days) were investigated using different analytical techniques. A mathematical model was used to analyze the kinetics of hydrolytic degradation of poly(3-hydroxyaklannoate)s by not autocatalytic and autocatalytic hydrolysis mechanisms. It was also shown that the degree of crystallinity of some polymers changes differently during degradation in vitro. The total mass of the films decreased slightly up to 8–9% (for the high-molecular weight PHBV with the 3-HV content 17.6% and 9%), in contrast to the copolymer molecular mass, the decrease of which reached 80%. The contact angle for all copolymers after the enzymatic degradation decreased by an average value of 23% compared to 17% after the hydrolytic degradation. Young’s modulus increased up to 2-fold. It was shown that the effect of autocatalysis was observed during enzymatic degradation, while autocatalysis was not available during hydrolytic degradation. During hydrolytic and enzymatic degradation in vitro, it was found that PHBV, containing 5.7–5.9 mol.% 3-HV and having about 50% crystallinity degree, presents critical content, beyond which the structural and mechanical properties of the copolymer have essentially changed. The obtained results could be applicable to biomedical polymer systems and food packaging materials.

Biodegradable Polylactide–Poly(3-Hydroxybutyrate) Compositions Obtained via Blending under Shear Deformations and Electrospinning: Characterization and Environmental Application

“…In this work, Bonartsev et al showed that the rate of hydrolytic degradation of PLA-PHB blend differed from the corresponding homopolymers. Most recently, in the paper of Bonartsev, Berlin, Iordanskii et al [56] it was demonstrated the impact of the PHB+HV (hydroxyvalereat) copolymer content on the hydrolytic behavior of the membranes. Additionally to the results obtained in aquatic medium, it would be interesting to explore the PLA-PHB compositions under fungi contact as the reasonable situation during contact the films with a microbial medium.…”

Natural-Based Biomaterials for Peripheral Nerve Injury Repair

“…-Long reabsorption time (over 2 years) (Mohanna et al, 2005). -Tendency to crystallization leading to reduced flexibility and ductility (Zhuikov et al, 2020). -Fragility and lack of hydrophilicity (Zhuikov et al, 2020).…”

“…Poly (3-hydroxybutyric acid) is the main polymer of the PHA family (Zhuikov et al, 2020). It is an innovative product of natural origin, obtained from bacterial fermentation, with potential characteristics including biodegradability and biocompatibility.…”

“…Since PHB has some disadvantages, such as fragility, lack of hydrophilicity and tendency to crystallize, characteristics which reduce flexibility and ductility of the conduit, the copolymer PHBV was made to compensate these disadvantages of PHB in order to improve the physic-chemical properties of that biomaterial (Zhuikov et al, 2020). In this way, mechanical properties can be modulated by co-polymerization of PHB with hydroxyvalerate to form PHBV biopolymer (Koller, 2018), considered more flexible and easier to process, even if it presents some disadvantages such as a narrow processing window and a low strain-at-break in comparison to petroleum-based synthetic polymers (Zhao and Turng, 2015).…”

Bio-Based and Biodegradable Plastics: From Passive Barrier to Active Packaging Behavior

“…A comprehensive study considering the physicochemical and mechanical behavior of pristine poly (3-hydroxybutyrate) PHB and copolymers of 3-hydroxybutyrate (HB) with 3-hydroxyvalerate (HV) during long-term enzymatic and hydrolytic biodegradation is presented by Bonartsev et al [ 2 ]. The evolution of principal characteristics such as polymer weight, its average molecular weight, crystallinity, and surface hydrophobicity as function of the HB/HV ratio is carefully described.…”